The present invention relates to a sheet post processing apparatus which accumulates sheets discharged from a copying apparatus or an image forming apparatus such as a printer, carries out binding process as stapling on sheet stacks, or alternatively offsets the sheet stacks per each of predetermined widths, and an image forming system having the sheet post processing apparatus.
The sheet post processing apparatus which disposes a process tray at an upstream side of a sheet discharge tray, aligns to accumulate the sheets delivered from the image forming apparatus on the process tray, carries out the post process as stapling on the accumulated sheet stacks, grips the sheet stacks by grip means (grippers), and discharges the sheet stacks on the discharge tray, has conventionally been known.
Japanese Patent Laid Open No. 2001-158564 (hereinafter “Patent Literature 1”) discloses the sheet post processing apparatus which disposes a staple tray 121 corresponding to the process tray at the upstream side of the discharge tray 112, accumulates the sheets delivered from the copying apparatus 2, carries out the stapling process on the accumulated sheet stacks by the staple apparatus 111, and thereafter pushes the sheet stacks at their back ends by a discharge pawls 110a corresponding to the grippers, thereby discharging the sheets on the discharge tray.
Further, Japanese Patent Laid Open No. 2003-89464 (hereinafter “Patent Literature 2”) discloses the sheet post processing apparatus where a grip means 21 circulating along rail grooves 3a discharges the sheet stacks accommodated in a sheet accumulation plate 5 to a stacker tray 4 being the discharge tray from the sheet accumulation plate 5.
Further, Japanese Patent Laid Open Hei No. 5-155176 (hereinafter “Patent Literature 3”) discloses the sheet post processing apparatus which, for carrying out the stapling process to the sheet stacks discharged and accumulated on a multi-stepped tray 1, uses a stapler assembled body 10 and gripper assembled bodies 11 mounted, as one body, on a supporter vertically moved by a motor 20, grips the sheet stacks discharged and accumulated on the tray 1 by a pair of gripping arms 28, 29 of the gripper assembled bodies 11, pulls the sheet stacks to the stapling position of the stapler assembled body 10, carries out the stapling process on the pulled sheet stacks, thereafter, again grips the stapling processed sheet stacks by the pair of gripping arms 28, 29 of the gripper assembled bodies 11, and returns to the original tray 1.
Still further, Japanese Patent Laid Open Hei No. 9-188470 (hereinafter “Patent Literature 4”) discloses the sheet piling and fixedly binding apparatus, where the sheet stack 14 is pushed at the end by the sheet end pushing and regulating mechanism 12, the end positioning member enables to change the position for regulating the end part at the binding side of the sheet stack 14 in the direction crossing with the end of the sheet stack 14, and is connected to move together with the sheet end pushing and regulating mechanism 12. The moving sheet stack fixedly binding mechanism is installed for binding the piled sheet stacks at the desired positions almost in parallel with the fixedly binding end of the sheet stack. The end positioning member has the size smaller than that of the flange opening 44 of the stapler, so that the end positioning member passes the stapler and moves without colliding with the stapler.
Yet further, Japanese Patent Laid Open No. 2002-128375 (hereinafter “Patent Literature 5”) discloses the accumulation apparatus where, when a blank material P becoming an under plate is delivered from a conveyor 2, a moving carriage 29 waiting backward of an end stopper 17 is directed to a conveyor exit. The delivered blank material is then received at the front end by a jaw portion 40 from an entrance and exit 43 and is supported at the underside by a supporter 44. As a support part 56 is pushed by the end of the blank material, lock pawls 53 are caused to hold the blank material. Further, when ending to hold the blank material, a sensor 60 causes the moving carriage 29 to be directed towards the waiting position with the same speed as the delivering speed of the conveyor, so that the jaw portion passes the end stopper. When the jaw portion passes the end stopper, the blank material collides with the end stopper, and the holding is released.
However, in the sheet post processing apparatus disclosed in Patent Literature 1, the staple apparatus 111 is moved to an appropriate position of the sheet stack whose back end is aligned by a back end fence 119, and after the sheet stack has been performed with the stapling process on a plurality of parts thereof, the stack is pushed by discharging pawls 110a on the sheet discharge tray, but since the sheet stack is merely dropped on the sheet discharge tray, there is a lack of proper alignment, which is drawback.
For moving the staple apparatus 111 to the appropriate position of the sheet stack, an apparatus mechanism is required for retracting the discharging pawls 110a from the moving range of the staple apparatus 111, and therefore, compacting of the apparatus is difficult.
Although, a substantially proper alignment can be obtained if the discharging pawls 110a is substituted by the sheet discharge mechanism by the grip means 21 disclosed in Patent Literature 2, such substitution may pose problems as outlined below.
A driving mechanism of the grip means 21 uses a circulating belt similar to a driving mechanism of the discharging pawls 110aof Patent Literature 1, and since the driving mechanism is always connected to the belt and turnably moves between the back of the staple position and the vicinity of an outlet of the sheet discharge tray, the grip means 21 are impossible to move. If a moving staple apparatus is mounted, the movement is disturbed, and, a control apparatus mechanism is required for retracting the grip means 21 from the moving range of the staple apparatus 111, and therefore, compacting of the apparatus is difficult.
Furthermore, if the moving staple apparatus is mounted on the discharging pawls 110a of Patent Literature 1 or the grip means 21 of Patent Literature 2, for solving the problem of disturbing the movement, and if the stapler assembled body 10 and the gripper assembled bodies 11 shown in Patent Literature 3 are made as a unit structure to move simultaneously, mutual hindrance while moving may be avoided. However, when the stapler assembled body 10 and the gripper assembled bodies 11 are made as a unit structure to move as disclosed in Patent Literature 3, the gripper assembled bodies 11 must be retreated within the moving range of the stapler assembled body 10. Further, under a condition where the sheets are once aligned and accumulated in a position different from the stapling position as mentioned above, the sheet stack is gripped by the grippers and pulled to the stapling position for the stapling process. Therefore, since the sheet stack is pulled to the stapling position, not only processing time is taken by this action, but also a proper stapling process cannot be performed since the aligned and accumulated sheet stack is broken down when pulling the sheet stacks to the stapling position.
Therefore, objects of the present invention are to obviate the above-mentioned drawbacks. Further, the present invention does not merely make a unit structure unified with the stapler means and the grip means, but rather divides into two functions of grip portions composing the grip means and a guide portion of guiding reciprocal movement of the grip portions. Further, according to the present invention, a cooperative and separable structure in association of the two functions with gripping actuation of the grip portions is provided. Further, according to the present invention, the grip portions are made as a unit structure unified with the stapler means, so that the above mentioned problems are solved.
Therefore, it is an object of the present invention to provide a sheet post processing apparatus where the grip means do not disturb a movement of the post processing means. Further, a sheet aligned condition is not broken down at the position of aligning and accumulating the sheets and a post process is possible within a short period of time. The grip means grip the post-processed sheet stack at the position of aligning and accumulating the sheets, and the sheet stack is discharged on a sheet discharge tray.
Further object of the present invention is to accomplish the below mentioned objects in the above mentioned sheet post processing apparatus and providing an image forming system having the same.
According to the present invention, the sheet post processing apparatus of a simple and compact mechanism is provided, where, when moving the grip means, it is not necessary to retreat a regulating means for aligning the sheets on the accumulation tray from the moving range of the grip means. Further, the grip means enable to receive the sheets under the condition of waiting for the grip means at the position of accumulating the sheet stack in the regulating means.
Further, according to the present invention, the sheet post processing apparatus of the simple mechanism and compact size is provided, where the grip means do not disturb moving of the post processing means and the aligned condition is not broken down at the sheet aligning position. The post process is possible for a short time and the grip means grip the post processed sheet stack at the sheet aligning position and enables discharge of the sheets on the discharge tray with a proper alignment. Further, the present invention provides the sheet post processing apparatus, where, by changing the moving speed of the grip portion in response to the moving position, when gripping the sheet stack, the gripping does disorder a registration of the sheet stack, when moving the sheet stack to the discharge position at high speed. Further, when discharging the sheet stack on the discharge tray, the discharging is possible to regulate at the discharge position.
According to another object of the present invention, control is performed at high speed with efficient regulation while discharging the sheet stack from an accumulation. Further, when accumulating the sheet stack onto the discharge tray, the speed is reduced to a low speed without affecting the regulation of the accumulated sheet. Further, the present invention provides the sheet post processing apparatus with an efficient sheet regulation on the discharge tray, and controls the speed of the grip portions of the sheet stack discharged onto the discharge tray at a regulation without performing complicated rotation speed of a motor.
In addition, the present invention provides the sheet post processing apparatus, where while delivering the sheet stack on the process tray to the stacker of the downstream side, even if an operator's finger or a foreign material goes into a path in a delivering course of the sheet stack, the apparatus does not go wrong or the operator is not injured. Further, with the sheet post processing apparatus of the present invention, where when accommodating the post processed sheet stack from the process tray to the stacker, even if the foreign material or the operator's finger are laid on the stacker, the operator is not injured and performance of the apparatus is not disturbed.
Further objects and advantages of the present invention will be apparent from the following description of the invention.